US2527331A - Hydraulic control mechanism - Google Patents

Description

Oct. 24, 1950 E. A. PUERN ER 2,527,331

HYDRAULIC CONTROL MECHANISM Filed Oct. 8, 1947 3 Sheets-Sheet 1 Oct. 24, "1950 E. A. PUERNER HYDRAULIC CONTROL MECHANISM 3 Sheets-Shet 2 Filed Oct. 8, 1947 INVENTOR. a. pawl/My,

Oct. 24, 1950 E. A. PUERNER 2,527,331

HYDRAULIC CONTROL MECHANISM Filed Oct. 8; 1947 a Sheets-Sheet s IN VEN TOR.

Q. Quiz/71M, BY

mmdlvmwm Patented Oct. 24, 1950 UNIT D. STATES PATENT OFFICE I 2,527,331 f I I HYDRAULIC CONTROL MECHANISM V .S'hallcross Controls, Inc., Milwaukee, Wis.,, a corporation of Wisconsin 7 Application October 8, 1947 Serial No. 778,685

' .5 claims. (01. (in-52) The control of the flow or pressure of fluids, both liquid and gaseous, is an essential factor the proper operation of many industrial plants, such as for example, those engaged in the manufacture of glass, 'metals,-chemicals and so forth.

At the present time electrically operated control mechanisms are commonly used for such pur-- poses. These electrically operated mechanisms are complicated and consequently are expensive to manufacture and-repair. d

'It .is, therefore, a general object ofthe present invention to provide a control mechanism ofthe' class described which is simple in design, :easy to manufacture, and which has a minimum of working parts which can get out of order.

A further object of the invention is to provide a control .mechanism which is hydraulically operated and which does not employ complicated gear reduction units. y

A further object of the invention is to provide an hydraulic control mechanism employing a very sensitive pilot valve therein which regulates the movement of an hydraulic'ram connected to a valve or damper [for controlling the flow of fluid throughaconduit. I. In conventional valves the valve stem thereof is subject to considerable starting friction and as a result it requires the application of .a much greater amount of force to initiate movementoi the valvestem than is required to keep the stem in ,motion once it has beenstarted with the result that it has not heretofore ,been possible to produce a valve for the type .of service under consideration which would .operate smoothly under the application of aeminimum of forcevthere to, both initially andafter movement'of the valve stem-had-commenced. l v

With the above in mind it is, therefore, am -object of the invention to provide a valve wherein the valve stem is moved -longitudinal-ly within arotating sleeve which maintains constant relative movement between itand the stem, even when the latter is at rest, thereby .negativing the inertia of the valvestem and producing a smooth and sensitive valve in which it is never necessan to apply undue initial force to break the stem loose of its enclosing sleeve.

A more specific object :of the invention ?is1t0 provide very high sensitivity in a valve byiree ducing the initial starting function of. the stem thereof to a negligible amount, thereby making thestem very accuratelyresponsivetofslight axial forces appliedto it. a

.A further object of the invention is to providean hydraulic control mechanism, including a pilot valve associated withafiuid pressure re-..

sponsive :means, which is particularly adapted for.

regulating the rate of flow of 2a tfluid through a conduit to thereby maintain a desired condition of ilowor pressure a't-a selected :point insaid con-.

du i t, regardless of fluctuations in the rate of introduction :of fluid into said conduit.

With the above and other objects .in view, the

3--3 of Fig. 1 and showing the pilot -valve stemin1 its neutral position;

Fig. 4. is a sectional View similar to Fig. 8, but.

showing different full and broken line positions of the pilot valve stem for 'the delivery of 'oilctoi the hydraulic ram, the raised position thereof.v

- being shown in f-ull lines, and-thelomredposition thereof being shownin bro'ken lines;

Fig. 5 is a diagrammatic view of the control mechanism adapted to control the flow of fluid in one conduit "and to maintain said flow in a selected ratio to the niow in as second conduit; and

Fig. 6 is =a diagrammatic view of the control mechanism adapted to control the pressure of fluid flowing in one conduit and to maintain said pressure in a selected ratio to the pressureof Ifiuid flowingin a second conduit.

Referring more particularly to Figs. -l to -4i inclusive of the drawings wherein is shown .an adaptation of the present invention tor maintaining the pressure oi a fiuidflovving through a conduit' at a selected l'eve'lgthe numeral [0 indicates a'metallic, oil tight container' having, in the pres ent exemplification, an open top and four vertically disposed sides which form substantially a square'in horizontal cross-section. Mounted on the exterior of two opposite sides of the container.

l1! are an electric motor H and agearpump L2; The shaftsof both the motor *I l and the pum-p IZ' extend into the interior of the-container I 0 and l are io'ined by ashatt lfi bymeansof suitablecou plings. Formed on the central portion of the 3 shaft I3 is a worm gear M. The inlet (not shown) to the pump I2 is located near the bottom of the container I0. Built within the pump l2 (and also not shown) is a conventional by-pass valve which, when pressure'in excess of a predetermined amount is built up at the discharge of the pump, the fluid atflthe discharge side of the pump is caused to be by-pased backto theinlet side of the pump. This prevents the building up of dangerous pressures which would otherwise be? built up by the gear pump l2. i p Mounted on the exterior of a third side of the container H! is a diaphragm assembly 15 which consists of a circular diaphragm" l6 of suitable flexible material securely peripherally mounted in air tight engagement between two. members l1 and I8 of the diaphragm housing. The side of the diaphragm l6 adjacent the member I1 is open to atmospheric pressure through the aperture H! which; extends through the member I! and the adjacent side of the container-I0. The side of the diaphragm l6 adjacent the member I8 is subject to the pressure exerted on it by fluids acting thereagainst through the aperture 2.-

.1 Disposed on either side ofthe diaphragm 6 and concentric therewith are metallic discs 2| having asubstantially smaller diameter than the diaphragm l6 and having outwardly turned peripheral edges. An actuating rod 22 having a threaded end extends through the centers of the discs 2| and the diaphragm l6. Suitable nuts 23 and washers 24 hold the discs2| and the diaphragm IS in close engagement and in addition furnish a connection between the discs =2| and the threaded end of the rod 22. I

Pivotally connected to the opposite end "of the rod 22 is'the upper end of a vertically extending leaf spring 25. Connected to the base of the spring 25 is a right'angularly extending portion 26, the :spring 25 and extension 26 being pivotally mounted, as at 21, for movement'in a vertical plane in the manner-of a bell crank lever.

Rotatably mounted adjacent the interior of a side'iof the container in. and opposite the side thereof on which the diaphragm .assemblyl is mounted, is a cam plate 28., w The. camplate 28 is connected, by meansof a suitable shaft extending through the side of container It], to a manuallyoperable knob29 having a pointer 30 which indicates. the positionof said cam plate with respect to a dial 3|. The edge surface ,of the cam plate 28 is in sliding contact with the end portion of the spring extension 26, the extension 26 being urged upwardly into said contact by a spring 32. Pivotally mountedon asuitable bracket 33, as at 38, for movement in a vertical plane, is a bell crank lever 34 having a vertically extending arm and a horizontally extending arm. The vertically extending arm of the lever 34 is pivotally connected to a link 35, as .at. 36, and the link 35 is pivotally connected to the rod 22 as at 31. The end. of the horizontally extending arm of the lever 34 is pivotally connected to a downwardly extending link 39, as at 40, and the lower end of the link 39 is pivotally connected, as at 43,- to the upper end of the stem 4| of a pilot valve,-generally indicated by the numeral 42. I

gThe pilot valve 42 consists of a substantially cylindrical body 45 which is axially vertically supported by a suitable bracket 44 which-is secured to a side of the interior of the container Ill. The body 45 is axially bored, as at 46, to slidably receive a rotatable-sleeve 41.- The sleeve 41 is prevented from sliding downwardly in the bore 46 by a retaining collar 48 whichis rotatable therea conventional balanced valve.

with and is connected thereto by any suitable means such as a set screw 49. A portion of the sleeve 41 extends below the body 45, and on this portion there is connected, by any suitable means such as a key 56, a helical gear or worm wheel 5|. The gear 5| meshes with the worm M on the shaft It. The sleeve v;4'| is formed; with four spaced exterior circumferential grooves 52, 53, 54 and 55 (see Figs. 3 and 4). Connecting each 'of the respective above-mentioned circumferential grooves with the bore of the sleeve 47 are spaced radial apertures 52, 53', 54' and 55. Extending radially through the body and registering with the respective circumferential annular grooves in sleeve 4'! are apertures 52", 53", 54" and 555.

The valve stem 4| is similar to that used in It is cylindrical in shape and is axially and rotatably slidable in the sleeve 4'|.v Adjacent its lower end the stem 4| is formed with a relatively wide external circumferential recess 56, and spaced above the recess 56 on the stem 4| is a similar, but narrower, recess 51. The recesses 55 and 56 result in the formation, on the end of stem 4|, of a collar 58, and, spaced upwardly therefrom a distance equal to the distance between the apertures 55 and 53 a collar 59. It will be noted that when the stem 4| is in the neutral position shown in Fig. 3. the collar 58 registers with and effectivelypow ers the aperture 55', and the collar 59 registersv ner end of the cylinder of a double acting hydraulic ram 63. The aperture 55" is tapped to threadedly receive a tube 64 which is threadedly connected at its other end to the outer end of the cylinder of ram 63. The numeral 65 indicates the conduit in which the fluid, the pressure of'which is to be regu-' lated, flows in the direction indicated by; the arrowsin Fig. 1. The pressure at any desired point, such as the point indicated by the numeral 66, is regulated by the adjustment of a damper 61 which is positioned within the conduit 65, and is pivotally I mounted on a rotatable shaft 68. Rigidly connected to an end of shaft '68 which extends exteriorly of the conduit 65 is an arm 69. A link 10 is pivotally connected 'to the arm 69, as at and pivotally connected as at 12 to the end of the piston rod 13 of the hydraulic ram 63. The aperture 20 in the diaphragm assembly l5 (see Fig. 2) is tapped to threadedly receive a tube 14 which at its other end is threadedly connected to the conduit 65 in the vicinity of point 66, as at 15. The container I0 is filled with oil substantiallyto the level indicated in Fig. 2 to form an oil bath or sump 15.

Operation it has been started.---The result is that "in conventio'nal structures a smoothlyoperating valve is practically an impossibility. The present invention reduces'the star-ting friction of the valve stem to a negligible amount by means of the constant rotation of the sleeve 41 main tains constant relative motion between it and the stem ll even though the stem 41 :may be fat rest. The result of this constant relative mo tion is that it is never necessaryto break the stem 4| freeof the sleeve 47 in order to move the stem 4| within-the sleeve. Substantiallyxall of the :axial force appliedxto ;the;ste1n;4| is effective to overcome the slight amount: of inertia inherent in the stem li and to thereby, easily move saidlstem. Since the inertia of the stem 41 is a relatively small factor, theystem 4.] can be moved very readily by theapplication oflvery slight amounts of axially applied forces. Asia result of this innovation a very smoothlyoperating valve is produced which is quickly res onsive to slight axial forcesand which is particularly well adapted for use in conjunction with sensi-' tive control mechanisms.

, When the pressure in the condui tffifi at the point 66 is at the desiredlevel indicated by the pointer 30 on the dial 3}, the entire control mechanism will be in equilibrium as shown in Fig. '2, and the stem '4"! of -the pilot valve will be in its neutral positionfas shown in Fig. 3. When this condition of equilibrium 'obtains,'jthe pres sure, in pounds persquare inch, at the-point -66, acts against the right hand side (relative "to Fig. 2) of the diaphragm it (through the tube 14') and is exactly equal "to the forces'acting in the opposite direction on the diaphragm 16. These opposite forces are those caused by atmos pheric pressure plus the pressure of the spring 25 acting against the driving rod 22 (disregarding pressures caused by Weight of the'va-lvestem 4 of thelinkage and so forth). When the stem 4 l is in its neutral position (see Fig; 3) the collars Stand-5t cover the ports 55uand v53' respec*- tively, thereby preventing oil flow therethitough, as pumpedbyJthe-gear pump through; thetube 60, the aperture 545, the annular groove; B l-and the aperture 54 into the recess 55 of the stem 4!. When this situation obtains, the by-pass valve built into the pump I2 acts torelievev excessive pressures as previously explained, since the .motor H and pump 12 are constantly running The pressure exerted on thediaphragm it by the rod 22 can be varied by means of rotating the cam 28. Depending upon which way the cam 28 is rotated (by means of the knob 'lS) theend portion of the extension '26, which is kept in contact with the edge of said cam by the spring 32, moves correspondingly upwardly or downwardly. As the extension 26 pivots on pin 2'], "the'spring 25 is urged in the same direction, resulting in deformation of the spring 25 which causes either a pulling or a pushing force to be exerted on the rod 22 by the spring 25, depending upon in which direction the spring 25 is urged by the extension 26. A rotation of the cam 28 while the control mechanism is in" a condition of equilibrium, results in a condition of unbalance, A condition of unbalance may also be brought about by a fluctuation in the amount of fluid flowing into the conduitliE. In actual practice, the position of the cam 28 changed'relatively infrequently and the control greases the control mechanism: 7

mechanism is used to maintain a constant pres sure at the point 66 regardless of the variations inthe amount of fluid delivered to the conduit Assuming that, with the mechanism in equilibrium, as shown in Figs. 2 and 3, the input, to the conduit 85 should suddenly decrease. As a result-of such decrease in input, the pressure at point 66 would decrease, as would the idem-- tical pressure acting against the right hand side (in-Fig. 2) of the diaphragm 1-5; The unbalance of forces acting on the diaphragm would then cause it to deflect toward the right, pulling with "it the actuating rod 2 2. Ihe unbalance ofiolcescacting on the diaphragm lt could quickly be corrected by an adjustment of the cam: 2a which would cause the spring 25 to exert Jessi-push on the -rod-'-2 2, but this-' -vrould nothing-toward the mainten-ance of --a constant pressure at tlie poin-t G6. Leaving the setting of the cam 28 at its original setting insu'ch a' case; would result in the following reaction by As the rod 2-2 moves toward the right-the link also moves toward the right, pulling with it the pivot 3t and the upper end of the vertical arm of the bell crank 3d. The bell c-r-an'k '34, as a result, pivots on pin '38 in-a clockwise direction (relative to thedrawing) and pulls upwardly on the link 39 and stem G! of the valve 42. The valve 42 will then have its stem ll-i in raised position, as shown in full lines in Fig. 4 When the stern il is in this position the oil pumped into the recess by the pump I2 is permitted to flow through: port 253', annular groove 53, aperture 53 and tube '62. Theaoil flow through the tube 62 is under pressureito the inner end of the cylinder of the hydraulic ram 63. This introduction :of oil into the cylinder under pressure causes-the ram towrnov outwardly (down in Fig. l)-. The :oil which is on the outer side of the' ram 63 is fOI Cefi-(flllt of the cylinder, as "the ram inoves outwardly, through the tube fi l-, the aperture 55 (see 4), the annular groove 55, "the aperture the lower endo'f the :interiorzof sleeve ilfh'iinto the oil bath or sump 15. The piston'scod, and the link it are moved in the same direction as the ram63 and thereby cause the arm fiepthe shaft. t8 and damper 16:? .to rotate in .a coun'zterclock-wise direction (relative to the :drawingsa; This rotation of the damper moves it to a posi tion wherein it exerts :less resistance to. flowliof fluid through the conduit 55 and consequently permits more fluid to pass itherethrough. yllvloi'te fluid passing through the conduit :causes :a

higher pressure at .point 68, which pressure :is

, communicated to the d'i'aiphragniilfi by tune MI;

As the ram gradually .moves outwardly the pres; sure at point gradually increases thereby causing the diaphragm and the rod .22 to be slowly moved toward the left (in Fig. 2). This gradual movement of rod 12-2 causes-simultaneous radual downward movement of the stem 4'! of the valve i z jand consequent simultaneous :gradua'l closing off "of the ports 55 and'53 by the collars 58 and 59 respectively. This, then, re sults in the gradual cessation of' flow of oil to the ram "63 and it is gradually brought to rest at the position-which corresponds to the posi= tion of the dam perlfihsaid Jp'osition bein 116C188 sary to maintain the desired pressure at .point '66. a 5

Shouldthe input of fluid to the conduit 65 increase, thereby raising thepressure at the 7 point 66 above that desired, the excess of pres-v sure will cause the diaphragm IE to deflectto the left (see Fig. 2). This deflection causes the rod22 to move toward the left (relative to the drawings), actuating the bell crank 34 in a counterclockwise direction and moving the stem 4| of the valve 42 downwardly to a position corresponding to that shown in dot and dash lines in Fig. 4.

When the valve stem 4: is in said lowered .position, the oil under pressure from the gear pump [2 flows from the recess 56 out of the aperture 55', through the annular groove 55, the tube 55" and into the tube 64. The tube 64 conducts the oil under pressure to the outer end of the cylinder of the ram 63. This causes the ram to move inwardly, forcing the oil on the inner side of the ram out through the tube 62 which leads to the aperture 53", the annular groove 53, the aperture 53 and the recess 51 of the Valve 42. This oil escapes from the recessfi'l through the aperture 52, the annular groove 52 and the aperture 52", spouting from the latter into the oil bath or sump l5.

As the ram 63 gradually moves upwardly, the damper 61 is gradually moved in a clockwise direction, thereby ofiering gradually increased resistance to the flow of fluid through the conduit 65 and thereby gradually lowering the pressure at-the point 66. The gradual lowering of pressure at point 66 permits the diaphragm Hi to gradually return to its normal unflexed or balanced condition. As the diaphragm I6 moves toward the right (see Fig. 2) toward its unflexed condition, the rod 22 also moves toward the right, causing the bell crank 33 to rotate clockwise and return the stern 4| to its central position (shown in Fig. 3), wherein the flow of oil to the ram 63 is shut off and the ram 63 is caused to come to rest. The position of the ram when at rest corresponds to the position of the damper 61 which offers sufficient resistance to flow of fluid in conduit 65 to maintain the pressure at point 66 at the desired level. The system is again in equilibrium, as shown in Fig. 2.

There are several other adaptations wherein the mechanism of the present invention can be used and which require only slight modifications. One of the most useful-of such adaptations is that shown diagrammatically in Fig. 5. Said viewillustrates diagrammatically a control for maintaining the rate of flow of a fluid in a conduit A in a selected ratio to the rate of flow of a fluid in a conduit B. The principle of operation of the control in this adaptation is similar to that of the mechanism shown in Figs. 1 to 4 and the same parts bear the same numbers as in those figures. A pair of diaphragm assemblies |5a and I5!) are employed instead of the single diaphragm assembly I5 shown in Figs. 1 and 2. The diaphragm of the assembly I5!) is linked to the spring by means of rod 22, as is the rod 22. The opposite end of the rod 22 is connected to the diaphragm of assembly I5a.

The rate of flow of fluid through a conduit can be measured by placing a disc therein having an orifice of known area through which all of the fluid flows. The differential between the pressure at a point upstream from the orifice and the pressure at a point downstream from the orifice is a function of the rate of flow through the orifice. An orifice 16 is formed in the conduit A downstream from the damper 61, and an orifice I1 is formed in the conduit B. A tube 14a leads from the outer cavity of the abet- :2

diaphragm assembly 15a to a point within the conduit B upstream from the orifice l1, and a tube 14a leads from the inner diaphragm cavity of assembly l5a to a point within the conduit B downstream from the orifice 1! as shown in Fig. 5. A' tube 141) leads from the inner dia-i phragm cavity of the assembly [5b to a point within the conduit A downstream from the orifice 16 and'a tube 14b leads from the outer diaphragm cavity of assembly I5b to a point within the conduit. A (upstream from the orifice 26. It will be noted that the inner diaphragm cavities of both assemblies I511 and 51) are not open to atmospheric pressure as was the case with diaphragm assembly 15 shown in Fig. 2. The upstream side of an orifice is always the high pressure side,'and it will be noted that with :the described arrangement the resultant deflecting forceon each of the diaphragms, due to the differential of pressures within the conduits, acts in an inward direction so that the deflections of the diaphragms of assemblies l5a and [5b act against one another through the rods 22 and 22. If no spring 25 were used, the mechanism would tend to maintain the flow in the two conduits at the same level. By loading the rods 22 and 22' with the selectively variable tension of the spring 25, the mechanism will maintain rate of flow of the fluid in conduit A at" a selectively variable ratio to the rate of flow of the fluid in conduit B. i

When the rate of flow of the fluid in conduit A drops relative to that of the fluid in conduit B, the rods 22 and 22' are moved to the left .by the diaphragms, and the spring 25 which movement, as described previously, actuates the valve 42 bymoving the stem 4| downwardly. This, in turn, causes the ram 63 to move inwardly and to rotate the damper 61 in a counterclockwise direction (relative to the drawing). Said movement of the damper 6'! permits more fluid to flow through the conduit A. The damper 6] isautomatically moved to a position in which it permits the rate of flow in the conduit A necessary to maintain the desired ratio between the rates of flow of the fluids in the conduits A and B.

When the rate of flow of fluid through the conduit A increases relative to that in conduit B, the rods 22 and 22' are moved by the diaphragm and spring 25 to the right. This causes the valve stem 4! to be raised and results in the ram 63 being caused to move downwardly to rotate the damper Bl in a clockwise direction. The damper 67 is rotated to a position wherein it decreases the rate of flow of fluid through the conduit A to the amount necessary to maintain the desired ratio of rates of flow in the two conduits. v

'Another adaptation of the improved mechanism is its use as a pressure proportioning control as illustrated diagrammatically in Fig. 6. This arrangement maintains the pressure of a fluid flowing in a conduit 0 in a selected ratio to the pressure of a fluid flowing in a conduit D. All parts of the mechanism of Fig. 6 serve the same purpose as the corresponding parts in Figs. 1 and 2 with the addition of a diaphragm assembly l5 identical with assembl l5 of Fig. 2. The diaphragm of assembly l5 islinked, by means of a rod 22, to the spring 25 as shown, and a tube 14' leads from the outer diaphragm cavity of assembly I5 to a point within conduit D. The conduit C of Fig. 6 is identical with conduit 65 of Fig. 1, other corresponding parts of the remain- -11 rotation of said sleeve by said shaft; a pressure responsive device adapted to be connected to a source of fluid pressure; a cantilever spring mounted opposite said pressure I responsive device; a pivotal mounting member to which one end of said spring is fixed; a manually operable adjustment member cooperable withpsaid mounting member to vary the position of rotation of said mounting member and the portion of the spring fixed thereto; a rod connecting the free end of said spring to said pressure responsive device; and linkage connecting said rod to' said valve stem in a manner 'to cause axial movement ofsaid stem in response to axial movement of said rod, whereby anoin'crease in the pressure to v which said pressure responsive device is subjected 'causes axial movement of said rod andstressing of said spring to thereby cause axial movement of the valve stem with resultant modification of the flow of oil from said oil pump through said valve and movement of said ram.-; v

5. In an hydraulic control mechanism, a tank; an hydraulic ram; a pilot valve mounted in said tank and connected to and controlling said hydraulic ram, said pilot'valve having a ported body formed with a borexa ported sleeve which is open at both ends and which is rotatably mounted in ';-,J'said bore; for rotational movement only, a drive {gear fixed to said sleeve, and a stem axially reciprocatably mounted within the bore of said sleeve; an electric motor; a shaft extending within said tank and drivinglyconnected at one'end to said motor; an oil pump drivingly connected to the 7 .other end of said driven shaft and having a discharge conduit communicating with said valve; a gear fixed to an intermediate portion of said driven shaft and cooperable with the valve sleeve -12 drive gear to cause rotation of said sleeve by said shaft; a pressure responsive device adapted to be connected to a source of fluid pressure; a canti-' lever spring mounted opposite said pressure-responsive device; a pivotal mounting member to which one end of said spring is fixed; a manually operable cam engageable with saidmounting member to vary the position of rotation of said mounting member and the portion of the spring fixed thereto; spring means urging said mounting member against said cam; a rod connecting the free end of said spring to said pressure responsive device; and linkage connecting said 'rod to said valve stem in a manner to cause axial movement of said stem in'response to axial movement of said rod, whereby'an increase in the pressure to which said pressure responsive device is subjected causes axial movement of said rod and stressing of said cantilever spring to thereby caus axial movement of the valve stem with-resultant modification of the flow of oil from said oil pump through said valve and movement of said ram. 1 ERVING A. PUERNER.

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Keller Oct. 7, 1941

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